cd <zabbix-src> && ./configure
cd ./src/modules
git pull https://github.com/am813nt/zabbix-fs-ro
cd zabbix-fs-ro && make
Copy <zabbix-src>/src/modules/zabbix-fs-ro/fs_ro.so zabbix-agent's LoadModulePath
Add LoadModule=fs_ro.so to zabbix_agentd.conf
Restart zabbix-agent
zabbix_agentd -t fs_ro.status
Key is fs_ro.status
.
It returns 1 if there is ext4 read-only filesystem and 0 otherwise. Based on that values trigger can be easily added.